An appeal to the legal definition is argumentum ad populum? Give me a break. You know what that means, don't you? It means an appeal to majority's sentiments and belief. (For example; common sense.) The law is not popular sentiment and belief.

If anything, the two of you insisting that it's only an assault if it results in substantial damage or that it should be governed by common sense is the argument to the masses. Pointing out that substantial damage is not a per-requisite for an assault isn't me appealing to the popular belief at all. It's me referring to the letter of the law.